1. Field of the Invention
The present invention relates to the field of optics and, in particular, to a device for splitting high-power light energy into a plurality of light beams. The United States Government has rights in this invention pursuant to Contract No. W-7405-ENG-48 between the United States Department of Energy and the University of California.
2. Description of the Related Art
Fiber optic power splitters are optical devices which distribute light energy from one optical fiber into several output fibers. An ideal power splitter would distribute the light energy to a given number of output fibers with no scattering loss and would remain insensitive to the amount of light energy transmitted to each output fiber. Based on these desired characteristics, two broad approaches to power splitters have been developed. See Arun K. Agarwal, Review of Optical Fiber Couplers, Fiber and Integrated Optics, Vol. 6, No. 1, 1987.
In the first broad approach, known as surface interaction type power splitters, each output fiber has a source end which is open to a common area where all or a portion of the light from a single input fiber enters the common area to be reflected or guided to each output fiber. Examples of this surface interaction approach are fused biconical tapered structures and mixer element star couplers.
Most applications of surface interaction type power splitters, however, are in low power information-distribution applications. This environment limits the kinds of information-distribution components that can be used and requires careful management of the optical power (light) to avoid damage to the components.
In the second broad approach, core interaction type power splitters, the power transfer takes place from the core of the single input fiber to the cores of the output fibers. Such a straightforward approach employs amplitude beamsplitters and focusing optics to split power from the core of the input fiber to the cores of the output fibers.
This core interaction approach works well for two output fibers. However, complex optical subsystems are required between the beamsplitters and the output fibers to insure satisfactory coupling. This renders the core interaction approach cumbersome and unwieldy when more than two output fibers are present.
One way of removing the complex optical subsystems required by the core interaction approach is to employ two fused silica microprisms and to fuse the fibers directly onto the prism surfaces (See Agarwal, pages 37-38, FIG. 10). Although this approach provides satisfactory coupling, it remains cumbersome when increasing numbers of output fibers are required. Thus, there is a need for a high-power, power splitting device which can easily distribute light energy to large numbers of output fibers.